1. Field of the Invention
The present invention relates to a microwave waveguide apparatus, a plasma processing apparatus and a plasma processing method.
2. Description of Background Art
Regarding an apparatus that generates plasma from gas using a microwave supplied to a waveguide, Japanese translation of PCT Laid-Open Patent Application No. 2002-526903 describes a plasma generator having a linear waveguide in which a long, narrow slot penetrating a wall in the waveguide is formed, and a microwave power source connected to this waveguide. In such a plasma generator, a microwave power source supplies microwave power to the waveguide to generate plasma in a slot.
Also, Japanese Laid-Open Patent Application No. 2012-64444 describes a plasma-generating apparatus structured to have a rectangular waveguide that is connected to a microwave-generating device and is long in a transmission direction of a microwave; a gas-supply device that supplies a processing gas into the rectangular waveguide; and an antenna unit that has multiple rectangular slot holes formed on one surface of the rectangular waveguide and that discharges plasma generated in the slot holes to the outside. In such a device, a standing wave is formed in the rectangular waveguide, and the slot holes that discharge plasma to the outside of the rectangular waveguide are formed at positions of a microwave corresponding to antinode portions of a standing wave in the antenna unit.
Japanese Patent No. 4900768 describes a plasma-generating apparatus having an annular resonator that resonates a traveling wave, and multiple applicators coupled to multiple couplers that direct the microwave and guide the microwave to a plasma-generating chamber (FIG. 1). In such an apparatus, as FIG. 2 shows, a directional coupler that guides a reflected wave propagated into the annular resonator to a dummy load is provided between an introduction waveguide and the annular resonator. The entire contents of these publications are incorporated herein by reference.